Thompson Grapes Problem Pics

lehua49July 8, 2008

Hi TG Growers and Anyone who knows bugs or diseases,

That should cover about everyone that gardens.

Here are some pictures of problems with my Thompson Grapes. What is wrong. Help. I don't want to spray because I have grapes growing.

There are ants moving up and down the vines as well. I'm sorry the two bugs in the last picture are blurry but I wanted to get close to see the shape and my camera doesn't focus that close. There is white powdery stuff all over the leaves and fruit or fine webbing I can't tell. Some leave's top layer of skin have been eaten off. The plant is still growing well and putting out new fruit stems. What would you do? None of my other plants close by have been affected.

Thank you for reporting this comment. Undo
fruitnut Z7 4500ft SW TX


Your Thompson is infected with powdery mildew. You will have to spray or dust sulfur or one of the systemic fungicides. This is the most widespread disease of grapes in CA. You need to start spraying early in the season. Spraying now will help but there will still be damage to the fruit. Sorry but if you don't want to spray you might as well rip your grapes out.

The Fruitnut

    Bookmark   July 8, 2008 at 5:19PM
Thank you for reporting this comment. Undo

I have the same thing on my thompson. Will it infect my Perlette that is across the yard?

    Bookmark   July 8, 2008 at 8:42PM
Thank you for reporting this comment. Undo
fruitnut Z7 4500ft SW TX


Most California grape varieties are suseptible. Some more than others. The breeders are working on resistant varieties but all now aval probably need spraying.

The Fruitnut

    Bookmark   July 8, 2008 at 10:38PM
Thank you for reporting this comment. Undo

Mahalo Fruitnut,

You are not so nuts after all. Anyone know the best method of spraying or brand of spray that kills powdery mildew. How would you apply a systemic. On the leaves directly or soaked in to the roots? Recommendations please.


    Bookmark   July 8, 2008 at 11:48PM
Thank you for reporting this comment. Undo
fruitnut Z7 4500ft SW TX


Commercial grape growers mostly use dusting sulfur. But that is primarily a cost issue. It is kinda nasty to apply and can damage the foliage under some conditions. I used to use wettable sulfur sprayed on other crops for powdery mildew. That would probably work here. When I was in CA I used Bayleton sprayed on the foliage and fruit. That is a systemic. I think there are more systemics but you would need to ask a knowledgeable sales person or someone else.

You might Google: grape powdery mildew control fungicide systemic.

The Fruitnut

    Bookmark   July 9, 2008 at 9:28AM
Thank you for reporting this comment. Undo
glenn_russell(6b RI)

I know very little about grapes other than the wild one which grows here on my property (and we eat them). But, for me, I've got a bad case of Powdery Mildew over here in Rhode Island, on multiple types of plants. Worst hit are some of my DR apple tress which are supposedly very resistant to PM. *sigh* I already gave them a sulfur treatment earlier in the season, but I'm not sure how much it helped. I thought sulfur was more of a protectant rather than an irradicant? Anyway, I decided to get tough and order systemic Immunox to see how that will work. I had wanted to experiment with Immunox anyway to see how it compared against Ferbam for Cedar Apple Rust next year. I had to order it online, as I couldnÂt find it at my 7 local nurseries. DonÂt be confused with "Immunox Plus" which is more widely available, but also has an insecticide which isnÂt rated for fruit. According to this link, it's very effective against PM for my apples:

According to this pesticide page, it is rated for grapes as a foliar treatment So, IÂm not sure what it means when you already have grapes:

According to this link, others are using it for grapes, and itÂs among their last seasonal sprays:

HereÂs the product homepage:

Note: I only ordered this yesterday, so I don't yet know the results of how effective it will be for me.

Again, to quote another poster, I know very little, but I did stay at a Holiday Inn Express last night. Please double check all my info before acting on it.

Other thoughts/opinions are welcome.


    Bookmark   July 9, 2008 at 11:10AM
Thank you for reporting this comment. Undo

Lehua, Thompson is problematic in the best climates, California for instance. There are lots of grapes that are more disease resistant than Thompson. Hawaii is a unique climate, to say the least. Your time would be best spent researching what varieties are already proven in Hawaii.

    Bookmark   July 9, 2008 at 4:39PM
Thank you for reporting this comment. Undo

Thanks everyone,

I am on the attack. Gotta save my grapes.


    Bookmark   July 9, 2008 at 5:23PM
Sign Up to comment
More Discussions
Beach Plum / Prunus Maritima Cultivation Questions
Hello all! I scarified a handful of seeds from beach...
liamkelly Zone 6b Rhode Island / 5b Massachusetts
Wisconsin honeyberry/haskap growers?
I'm combining the two as it seems with continued breeding...
Help understanding huckleberries
I recently enjoyed some huckleberry pie and was pleasantly...
Any idea what's causing this on my blueberry?
A couple of the newer branches are turning black at...
ferroplasm Zone 7b
Blue Berries-acid soil and other vegetable plants
I have been growing blue berry plants intermixed with...
Sponsored Products
Thompson Traders Bathroom Handmade Vessel Sink with Apron in Brushed Nickel
Home Depot
Quoizel Thompson LED Brushed Nickel Desk Lamp
Lamps Plus
Hudson Valley Lighting | Thompson Round Vanity Light
$300.00 | YLighting
Thompson Indoor Rug - 2' x 3'
Grandin Road
Thompson Chair SE by Gus Modern
$254.15 | Lumens
DaVinci Thompson 4-in-1 Crib with Toddler Rail
Thompson Oushak Rug 9' x 12'
$5,199.00 | Horchow
Vivid Thompson Dark Bronze with Antique Gold LED Table Lamp
$189.99 | Bellacor
© 2015 Houzz Inc. Houzz® The new way to design your home™